1. Field of the Invention
The present invention relates to the field of retail store checkout systems and more particularly to shopping cart bottom of the basket detection.
2. Description of the Related Art
Retail stores suffer millions of dollars of losses each year as a result of the theft of products occurring when customers intentionally or accidentally conceal items on the lower tray of their shopping carts. Retail stores are particularly vulnerable to this problem because store cashiers cannot observe the lower tray of the shopping cart from a store cashier's normal position. Although store cashiers can inspect the contents of the lower tray of a shopping cart by leaning over the checkout counter, this motion poses an inconvenience to the cashier. Furthermore, customers may consider as rude this potentially mistrustful display. Thus, retail stores having multiple cashiers and multiple checkout aisles with multiple checkout counters need a system which would allow the inspection of the lower tray of a shopping cart without needlessly inconveniencing the store cashier, or unintentionally offending the customer.
Several systems have been developed to alert a store cashier to the presence of a parcel positioned on the lower tray of a shopping cart as that cart passes through the checkout aisle. U.S. Pat. No. 4,327,819 issued to Coutta on May 4, 1982 for OBJECT DETECTION SYSTEM FOR A SHOPPING CART, U.S. Pat. No. 4,725,822 issued to Hooley on Feb. 1, 1988 for SHOPPING CART WITH LOWER TRAY SIGNALING DEVICE, and U.S. Pat. No. 4,736,098 issued to Rehrig on Apr. 5, 1988 for SIGNALING METHOD AND APPARATUS FOR A CONVENTIONAL SHOPPING CART each disclose systems whereby a combination of a light transmitter, light detector and a reflector mounted on the lower tray of a shopping cart act in concert to detect the presence of unpaid for articles on the lower tray of a shopping cart passing through a checkout aisle. Unique to the systems described in the these patents is the use of springs which bias the lower tray towards one position so that the increased weight of parcels placed on the lower tray depresses the tray, bringing the reflector into the path of the beam of light emitting from the transmitter.
In recent years, inventions disclosed by several patents have implemented lower tray detection systems using light transmitters and detectors positioned on either side of the checkout aisle. As a result, this type of system eliminates at least the retrofitting requirement of prior systems. In particular, U.S. Pat. No. 5,485,006 issued to Allen et al. on Jan. 16, 1996 for PRODUCT DETECTION SYSTEM FOR SHOPPING CARTS, U.S. Pat. No. 5,495,102 issued to Fine on Feb. 17, 1996 for SHOPPING CART MONITORING SYSTEM, and U.S. Pat. No. 5,610,584 issued to Schrade for DETECTION OF GOODS ON THE BOTTOM RACK OF A CART each include systems having infrared lights sources and detectors positioned across the width of a checkout aisle.
Conventional bottom-of-the-basket (BOB) detectors can require some sort of constant monitoring by checkout personnel. Conventional BOB detectors further can require expensive hardware investments and time consuming shopping cart retrofits in order to accommodate the complicated imaging sensor systems. For many BOB detectors, the cost of the sensing camera can be enormous dissuading widespread adoption. Likewise, more complex detection equipment often translates into substantial training costs for checkout personnel.